Use of cellular and other wireless types of communication devices have become more commonplace. Entire networks have been established for processing communications signals transmitted and received by cellular phones. Initially, the only types of information processed by the network were audio information and limited amounts of alphanumeric information relating to the processing of telephone numbers.
As digital technology has advanced, the amount of information which may be transmitted and received by wireless telephones has increased. For example, wireless telephones are now able to process and display alphanumeric information. This information is presented through a small screen incorporated into the telephone.
One feature which has recently been incorporated into some cellular or wireless telephones is the functionality to process information received and transmitted over a data network such as the World Wide Web. The main limitation of these small handheld devices is that only a few lines of alphanumeric information may be displayed at one time, there is a limited key pad for entering information, and most handheld devices do not have the types of memory resources which allow for processing of information received from servers connected to a data network such as the World Wide Web.
In order to accommodate the use of handheld devices for accessing information over a data network, a processing language called Handheld Device Markup Language ("HDML") has been developed. This language is especially suited for formatting Web content for the bandwidth or display size constraints of a handheld device. Whereas the fundamental structural unit of HTML is a page, in HDML, the fundamental unit is a deck of cards. Each HTTP response from a web server is packaged in the form of an HDML deck. A deck may contain one or more cards, each which specifies a single interaction between the device and the user. Some examples of the types of information provided include displays of information, display of a prompt which lets a user enter a string of inputs, displays a list of options for user to select, and the performance of various hidden operations.